alkorn Posted November 16, 2004 Report Share Posted November 16, 2004 I've just started building a Stevenson Triad and want to use some rig other than the standard lateen. I have two reasons for this: I don't find the lateen rig very attractive, and I'd like to get more sail area onto the boat. Based on the Stevenson plans, I've drawn up the Triad with the lateen rig (http://filebox.vt.edu/users/alkorn/Triad%20Lateen.pdf). The center of effort of the rig appears to be almost directly above the centerline of the daggerboard. I found this suprising, since from what I've read the center of effort should be a little forward of the center of resistance to avoid excessive weather helm. The only way I can think of to explain this is that with crew in the cockpit the stern sits low, moving the center of resistance aft of the daggerboard. I'd like to hear from anyone who's sailed the Triad with the standard rig. Does it show weather helm? Anyhow, I've drawn up a gunter rig (http://filebox.vt.edu/users/alkorn/Triad%20Gunter.pdf) with 82 sq ft area as opposed to 66 for the lateen. The center of effort is on the same line as that of the lateen and only about 7 inches higher up. It seems to me this is the most sail area I can get on the Triad without either moving the center of effort futher aft, using a mast longer than 12 ft, or adding a bowsprit. I've also drawn up the gunter rig reefed (http://filebox.vt.edu/users/alkorn/Triad%20Gunter%20Reefed.pdf) down to a total area of 57 sq ft. Unless I get serious advice to the contrary or get a better idea before I finish the hull, I'm going to rig the Triad with this gunter setup. Any and all comments and advice will be appreciated. I'd especially like to hear from anyone who has experience sailing the Triad. (Incidentally, I drew up these plans with the "Instant Architect" CAD package I bought my daughter last year. Though it is really meant for designing houses, it has some nice features including automatically faired lines, automatic calculation of areas, and automatic calculation of centroids.) Quote Link to comment Share on other sites More sharing options...
Frank Hagan Posted November 16, 2004 Report Share Posted November 16, 2004 Alkorn, we're pretty pro-experimentation around here, so I don't think anyone will try to convince not to "mess with the designer's plans" (the Stevensons' even feel that way!) But I don't know of anyone that has done this with the Triad. You probably won't get much in the way of a specific response, but mainly some conjecture like I'm about to give. I do think that your suspicion is probably right regarding the center of resistance. On such a light boat, the helmsman does have a great effect. One of the hallmarks of the Stevensons' designs is that they develop them through sea trials. They start with a design, then build a very cheap full size model of it, try it, refine it, and do how ever many iterations of that process to get the performance they are looking for. So, I suspect the surprising results when the calculations are done are really the result of trial and error. Peter Stevenson has said he believes all the calculations are an attempt after the fact to explain why boats work, and while some things can be reduced to formulas, designing a boat is still part science, part art. You've done the science part, and considered the appearance of the boat, and only when you actually get her onto the water will you know for sure. In other words, "go for it". Quote Link to comment Share on other sites More sharing options...
Cactus Willie Posted November 19, 2004 Report Share Posted November 19, 2004 Last year I built a Skipjack and put a gaff rig on it and did fine. But I did not like messing with the peak halyard. So I redid it with a Lateen Sloop combination. You can see it at my homepage....homepage.mac.com/charlescasterline It sails fine. Looks almost like your gunter rig. If you go to the site I have a video done so you can see it sailing. Quote Link to comment Share on other sites More sharing options...
Stump Posted November 20, 2004 Report Share Posted November 20, 2004 Hey Cactus Willie!! Nice site. Great video and pictures! Quote Link to comment Share on other sites More sharing options...
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